We are studying the enzymatic and molecular mechanism of general genetic recombination in E.coli. Several of the pathways for genetic recombination in E.coli have been shown to mediate the interconversion of certain plasmid DNAs and their circular oligomeric forms. Assays that measure the interconversion of plasmid DNAs and their circular oligomeric forms in vitro have been developed, and studied. The Rec A has been purified and the Rec F protein will be purified using an in vitro complementation assay which measures the ability of these proteins to complement the effect of the rec A and rec F mutations on plasmid DNA oligomer metabolism in vitro. The Rec A protein, the Rec BC protein (exonuclease V), the Rec F protein and the Rec E protein (Exonuclease VIII) will be used in reconstitution assays to purify unknown proteins that are involved in the Rec BC, the Rec E, and the Rec F pathways of genetic recombination in E.coli. DNA sequences which promote high levels of plasmid DNA circular oligomer formation will be isolated and the interaction between these DNA sequences and purified recombination proteins will be studied.